In the wake of the deadly London terrorist attacks, British Home Secretary Charles Clarke says millions of personal e-mail and mobile phone records could be stored and shared with police and intelligence officials across Europe to help thwart future attacks, according to an Observer report.

Clark claimed that such communications could "quite possibly" have helped prevent such attacks by identifying in advance suspicious patterns of behavior by potential terrorists.

The British government's action is part of a wider EU initiative to have the continental collective spy on its citizens' emails and cell phone calls.

Meanwhile, according to the Observer report, the National Crime Squad has contacted Internet service providers in the U.K., appealing to them to preserve e-mail messages in case they prove useful to the manhunt for those responsible for last week's attacks.

Clarke's proposal for an EU-wide agreement would stop short of intrusion into the content of e-mails, but would require the storing of revealing "traffic data" - detailing who has called, or messaged whom, with times and locations - for several years.

"Terrorism today is by definition international: The more we can survey the way in which people operate, the way in which they make their phone calls, the better your chance of identifying patterns of behavior which are a threat," Clarke said.

Simon Davies, director of Privacy International, said some EU countries, including Germany, were likely to resist. "There are some celebrated cases where we know, for example, that traffic data and mobile location [have] been useful to the police," he said.

"But this is mass surveillance at its crudest. It would lead to 'information overload'," he said, stockpiling masses of useless information.

David Davis, the shadow home secretary and frontrunner to lead the Conservative Party, warned in an interview yesterday that civil liberties should not be sacrificed in the rush to defend Britain.

"The best defense of security is to have the liberties," he said. "The first act of the liberation fighter is to try to force the state to do repressive things, because when the state does repressive things it recruits your supporters.